Turbine driven centrifugal compressor unit



y 1965 w. E. TRUMPLER 3,132,897

TURBINE DRIVEN CENTRIFUGAL COMPRESSOR UNIT I Filed April 12, 1963 5Sheets-Sheet 1 10 INVENTOR.

WIgI JAM E. TRUMPLER ATTORNEYS May 11, 1965 w. E. TRUMPLER TURBINEDRIVEN CENTRIFUGAL COMPRESSOR UNIT Filed April 12, 1963 s Sheets-Sheet 2May 11, 1965 w. E- TRUMPLER 3,132,897

TURBINE DRIVEN CENTRIFUGAL COMPRESSOR UNIT Filed April 12, 1963 3Sheets-Sheet I5 INVENTOR. WILLIAM E. TRUMPLER Q MJM ATTORNEYS UnitedStates Patent 3,182,897 TURBINE DRIVEN CENTRIFUGAL COMPRESSOR UNITWilliam E. Trumpler, ()lean, N.Y., assignor to Dresser industries, Inc,Dallas, Tex., a corporation of Delaware.

Filed Apr. 12, 1963, Ser. No. 272,660

9 Claims. (Cl. 230-116) This invention relates to improvements in aturbine driven centrifugal compressor unit, and more particularly to ahermetically sealed high speed turbine driven high pressure centrifugalcompressor unit.

A primary purpose of the present invention is to provide apparatus whichwill. compress a gas which is already at a high pressure such as 20,000pounds per square inch (hereinafter referred to as p.s.i.) to a stillhigher pressure such as 40,000 psi.

When handling gas at such high pressure levels in apparatus havingrelatively movable parts, it is impossible to seal against the leakageof gas past such parts. Another object of the present. invention istherefore to provide such apparatus which is hermetically sealed withrespect to the environmental medium surrounding the apparatusnotwithstanding unpreventable internal gas leakage.

In the handling of certain gases such "as ethylene, it is undesirable tolubricate'relativelyrotating parts such as bearings with conventionallubricating oils or greases inasmuch as such lubricant will contaminatethe gas. Effective protection against frictional effects between therelatively rotating parts is still required, however, because of thehigh rotative speed of the rotor in the inventive apparatus, which speedtypically may be 70,000 r.p.m. Accordingly, another object of thepresent invention is to provide. such apparatus which avoids usingconventional liquid lubricants and employs the gas being handled.

to effectively lubricate 'the relatively'rotating parts.

Another object is toprovide such apparatus in which the gas lubricatedbearings are supplied with the inevitable internal gas leakageaforementioned.

Another object is to provide such apparatus which is so constructed asto eliminate any end thrust by the rotating elements.

Another object is to provide such apparatus which handles inlet gas at ahigh pressure and compresses it to' even higher discharge pressure in anefiici'ent manner.

Other objects and advantages of the present invention will be apparentfromthe following detailed description of a preferred embodiment shownin. the accompanying drawings in which:

FIG. 1 is an end elevational view high speed turbine driven highpressure centrifugal compressor unit constructed in accordance with theprinciples of the present invention. 7 i

FIG. 2 isa vertical central sectionalview thereof taken on line 22 ofFIG. 1, certain internal parts being shown in elevation. i a 7 FIG. 3 isan enlarged fragmentary vertic'al central sectionalview thereof,generally similar to FIG. 2.

FIG. 4 is a fragmentary vertical transverse sectional viewthereof takenon line 4-4 of FIG. 3.

FIG. S is a fragmentary vertical transverse sectional viewthereof takenon line 55 of FIG. 3.. a

FIG. 6 is a fragmentary vertical transverse sectional view thereof takenon line 66 of FIG. 3.

The turbine jdriven centrifugal compressor unit is shown as comprising ahousing including a cylindrical barrelv section 10 having transverseflat end surfaces to which end heads 11 and 12 are removably secured.Each ofthe end heads 11 and 12 is shown as provided with axiallyextending holes 13 through which the shanks of machine screws 14 extend.The ends of these screw shanks are externally threaded and received ininternally of a hermetically r 3,182,897 Patented May 11, 1965 threadedrecesses 15 provided axially in each end of the barrel section 10. Aplurality of such screws 14 arranged at circumferentially uniformlyspaced intervals, as shown in FIG. 1, are employed for securing each endhead to the barrel section.

Rotatably arranged completely within the housing is a shaft representedgenerally by the numeral 16. This shaft is symmetrically formed aboutlongitudinal and transverse centerlines and is shown as including anenlarged, generally cylindrical central section 18. Similar cylindricalsections 19 and 20 of slightly reduced diameter are arranged on oppositeaxial sides of the central shaft section 18. Similar further slightlyreduced cylindrical sections 21 and 22 are arranged axially outwardly ofthe cylindrical sections 19 and 20, respectively. The shaft alsoincludes similar cylindrical sections 23 and 24 of still furtherslightlyreduced diameter arranged axially outwardly of the cylindricalsections 21 and 22, respectively. In addition, similar generallycylindrical sections 25 and 26 of even further reduced diameter arearranged axially outwardly of the last mentioned centrifugal sections 23and 24, respectively. The extremiites of the shaft are formed as reducedexternally threaded stems 27 and 28 which extend axially outwardly fromthe outer ends of the sections 25 and 26, respectively.

Centrally arranged on the shaft 16 so as to rotate therewith is animpeller indicated generally at 29. This impeller includes a hub portion30 and an integral central radially extending annular disk-like portion31. The hub portion 30 is shown as formed with an axially extendingthrough hole 32 which is so dimensioned as to have a press fit with thecentral shaft section 18 whereby the impeller and shaft rotate together.Any other suitable mode of non-rotatively fastening the impeller 29 tothe shaft 16 as by keying or splining may be employed but it shouldpreferably be diametrically symmetrical so as to maintain the dynamicbalance of the shaft.

The central shaft section18 is shown as provided with two pairs ofdiametrically opposed, axially extending uniformly circumferentiallyspaced through grooves 33. These grooves 33 establish communicationbetween'opposite axial sides of the central shaft portion 18 for apurpose explained more fully infra.

l The annular radial portion 31 of the impeller 29 is shown as providedwith symmetrical blading on opposite axially facing sides thereof. Asshown in FIGS. 3 and 5, each side of the impeller is provided with aseries-of circumferentially and uniformly spaced,radially; extendingblades 34 which are preferably formed integrally with the radialimpeller portion 31 and these blades 34 are shown as integrally joiningat their outer ends to provide transverse paddles 35. 'The hub portion30 and radial portion 31 of the impeller are shown joined by a smoothlycontoured fillet as indicated at 36, the blades 34 beginning at theirradially inner ends at about the radially outward terminations of suchfillets36.

Surrounding the periphery of the impeller 29 and arranged symmetricallywith respect thereto is a diffuser ring 38. This ring 38 is shown assupported on shoulders 39 of a pair of stationary housing inner rings 40and 41. These rings 40 and 41 have anputer diameter corresponding tothat of the diffuser ring 38' and are slidably end's'urfaces of therings 40 and 41 are spaced apart to' provide with respect to theinterposed impel1er.29 a

, chamber 43 associated with the ring 40 and a similar therebet-ween.The rings 40 and 41 have fiat radially chamber 44 associated with thering 41. The radially inner portion of the rings 40 and 41 are providedwith a rounded contour as indicated at 45 which opposes the fillets 36on the impeller so-as to leave a passage 46 extending outer axiallyfacing surfaces 48 which severally connect through a rounded contourindicated at 47 with the previously mentioned rounded contour 45.

Axially spaced outwardly of the housing inner rings 40 and 41 arestationary housing intermediate rings or diaphragms 49 and 50,respectively. Arranged axially outwardly of these rings 49 and 50 arestationary housing outer rings 51 and 52, respectively. The rings 49-52have an outside diameter corresponding to that of the barrel bore 42 sothat these rings may be slid in and out of the housing barrel section10.

The opposing axially facing sides of the housing intermediate rings 49and 50 follow the shape generally of the corresponding opposing surfaces47 of the inner housing rings 40 and 41 so as to provide passages 53therebetween. In order to maintain such spaced relation, each of therings 49 and 50 is formed preferably integrally with streamlinedradially extending lugs or vanes 54, as best shown in FIG. 6. These lugs54 are shown as circumferentially uniformly spaced to leave passages 55therebetween which communicate with the passages 53. The outer ends ofthese passages 55 communicate with an annular recess. One such recess 56is formed between the rings 40 and 49 and a similar recess 58 is formedbetween the rings 41 and 50. The recesses 56 and 58 are severally incommunication with radial passages 59 and 60, respectively, which extendradially through the housing barrel section 10.

Intermediate these radial passages 59 and 60, the housing barrel sectionis also shown as provided with another radially extending passage 61.The inner end of this passage communicates with an annular recess 62formed on the internal surface ofthe barrel section 10. i This recess 62jointly with the peripheral surface of the diffuser ring 38 provides acollecting chamber. This chamber communicates with the periphery of theimpeller 29 through a series of circumferentially spaced, generallytangentially extending slots 63, as best shown in FIG. 5.

The communicating passages 59, 56, 55, 53 and 46 establish an inletconduit to the blading on the left side of the impeller 29 as viewed inFIG. 3. The communicating passages 60, 58, 55, 53 and 46 provide aseparate inlet conduit leading tothe blading on the right side of theimpeller 29 as viewed in FIG. 3. The communicating passages 61, 62 and63 provide an outlet or discharge passage for gas compressed by theimpeller 29.

Referring to FIGS. 1 and 2, means are shown for attaching supply anddischarge lines to the various passages 59-61 in the housing barrelsection 10. For this purpose, the barrel section is shown as formedcentrally with a fiat surface 64 against which seats the flat surface ofan attaching flange indicated generally at 65. This flange 65 is securedto the housing barrel section by several machine screws 66, four suchscrews being shown. Although not illustrated but readily understood,each of these screws 66 has a shank threadedly received in a recessformed in the barrel section 10. The flange 55 is shown as integrallyformed with inlet nipples 68 and 69 which severally and respectivelyaline with the inlet passages 59 and 60 in the barrel section. Theflange 65 is also shown as provided with a nipple 70 which alines andcommunicates with the discharge passages 61 in the barrel section.

Preferably, as 'shown, 'a pair of freely rotatable plates or covers 71and 72 are arranged on opposite axial sides of and coaxially with theimpeller 29. The plate 71 is shown as arranged in the chamber 43 on theleft hand side of the impeller 29, as viewed in FIG. 3, and the otherplate 72 is arranged on the right hand side of this impeller in thechamber 44. Each of these plates 71 and 72 has a flat generally radialsurface which is closely spaced to the land surfaces of the blading 34.The radially inner end of each plate 71 and 72 is shown as formed withan axially outwardly extending hub or annular flange portion 73 whichsurrounds and rotatably engages a coaxial sleeve portion 74 of a firstbearing ring 75 associated with the plate 71 and a similar sleeveportion of a second bearing ring 76 associated with the other plate 72.Each of the bearing rings 75 and 76 has a radially outwardly extendingannular flange portion 78. These portions 78 oppose the end faces of thehubs 73 of the plates 71 and 72, respectively, and absorb any end thrustexerted by these plates. The bearing rings 75 and 76 are supported onsuitable shoulders formed on the housing inner rings 40 and 41,respectively. Referring to FIG. 3, it will be noted that the inner andopposing ends of the sleeve portions 74 of these bearing rings 75 and 76are rounded in contour to follow generally the configuration of theopposing impeller fillets 36 and to form coterminous extensions of therespective rounded surfaces 45 on the housing rings 40 and 41.

Preferably the bearing rings 75 and 76 are composed of aself-lubricating material which will not require conventional oil orgrease lubrication between the relatively rotating surfaces of thesebearing rings and the freely rotatable plates 71 and 72. The preferredmaterial of which the bearing rings 75 and 76 is composed comprises longchain fiuorinated polymers of ethylene such as tetrafluoroethylene whichis known in the trade as Teflon. Such a material has dry,self-lubricating properties.

The outer or peripheral edges of the plates 71 and 72 are severallyshown as having radially outwardly extending offset annular flangeportions 79 which severally overlap radially inwardly extending annularflange portions 80 integrally formed on the dilfuser ring 38 on oppositesides of the diffuser slots 63. Thus the axially spaced annular diffuserring flanges 80 form a gas collee-ting groove 81 which communicates withthe groove 62 via the several slots 63 which extend through the diffuserring 38 at circumferentially spaced intervals.

Gas type sleeve bearings 82 and 83 are provided for ournalling the shaft16 inwardly of each thereof so as to leave overhung shaft end portions.The bearing 82 is shown as surrounding the cylindrical shaft portion 21.The other bearing 83 is shown as surrounding the cyl1ndrical shaftportion 22. The bearings 82 and 83 are shown' as supported on tubularmembers 84 and 85, respectively, in turn supported on the housing outerrings 51 and 52, respectively.

Means are shown for supplying leakage gas from the inlets for theimpeller 29 to the opposing closely spaced peripheral surfaces betweenthe bearing 82 and shaft section 21 and between the bearing 83 and shaftsection 22. For this purpose, radially inner portions of the opposingaxially facing surfaces of the housing rings 49 and 51, including theexposed end face of the tubular member 84, are spaced apart to provide achamber 86. A similar chamber 88 is provided between the opposing andspaced surface portions of the housing rings 50 and 52, including theexposed end face of the annular member 85. It will be noted that thelugs 54 on the housing intermediate rings 49 and 50 keep the radiallyinner and opposing end surface portions of these rings axially spacedfrom the opposing end surfaces of the hub portion 30 of the impeller 29so as to leave an annular clearance 89 to the left of the impeller, asviewed in FIG. 3, and a similar annular clearance 90 on the right sideof this impeller. Intermediate the clearance 89 and the chamber 86,housing ring 49 is shown as internally formed with labyrinth seal means91. The ridges of such labyrinth seal means 91 are closely spaced fromthe opposing periphery of the cylindrical shaft section 19. A similarlabyrinth seal means 92 surrounds the cylindrical shaft section 20intermediate the clearance 90 and chamber 88.

Each of the sleeve bearings 82 and 83 is shown as provided withanannular groove 93 in its outer periphery. Communicating with this groove93 in each bearing is a series of circumferentially spaced radial holes94, four such holes being typically'provided for each sleeve bearing.Also, each annular groove communicates with several circumferentiallyspaced axially extending grooves 95. In the case of the bearing 82, thegrooves 95 open to the annular chamber 86. The grooves 95 in the bearing83 open to the annular chamber 88.

In this manner, inlet gas under a high pressure can flow through theclearances 89 and 99 past the labyrinth seal means 91 and 92 into thechambers 86 and 88, respectively from whence this gas can communicatethrough the connected passages 93-95 with the slight annular clearancethat exists between the opposing peripheral surfaces of the bearings andshaft. The inner ends of the radial passages 94 and the bearings serveas orifices which are variably closed depending upon the relative radialposition of the opposing shaft periphery. Gas escaping through theradial passages 94 will float the shaft on an annular film of gas toprovide a dry journalling of the shaft which will not requirelubrication by conventional liquid type lubricating materials such asoil or grease but which will be lubricated by the gas film so provided.

Provision is made for conducting any gas leaking outwardly past thebearings 82 and 83 to the inlets to a pair of similar turbine wheels 96and 98. The turbine wheels 96 and 98 are shown as suitably non-rotatablymounted on the shaft sections 25 and 26, respectively. For this purposethe hub of the turbine wheel has an axially extending through hole 97which has a press fit with the corresponding cylindrical shaft sections25 or 26. Any other suitable fastening such as keying or splining,preferably diametrically symmetrical, may be employed. The turbine wheel96 is shown as held against the shoulder formed by the shaft sections 23and 25 by a nut 99 screwed onto the threaded stem 27. A similar nut 100is screwed onto the stem 28 at the other end of the shaft to hold theother turbine wheel 98 against the shoulder formed by the shaft sections24 and 26.

The turbine wheels 96 and 98 are shown as being of the radially inwardflow type. Thus each such turbine wheel is shown as comprising a diskportion 101 from one side of which vanes 102 extend. The vanes 102, bestshown in FIG. 4, are arranged on the axially outer surface of the diskportions 101 so that the turbine wheels 96 and 98 effectively face inopposite axial directions or back to back.

A suitable interlocking seal means indicated at 103 is provided betweenthe opposing end surfaces of the turbine wheel hubs and the cylindricalmembers 34 and 85 supported on the housing outer rings 51 and 52,respectively. These cylindrical members 84 and 85 are shown as beinginternally provided with labyrinth seal means 104 and 105, respectively,to hold back leakage axially outwardly past the bearings 82 and 83.However, some leakage will occur.

In the case of the left end of the shaft as shown in FIG. 3, suchleakage is collected in an annular groove 106 formed on the internalsurface of the member 84 adjacent its outer end. A series of radialholes 103 through this member 84 severally communicate at their innerends with the groove 106 and at their outer ends with an annular groove109 provided in the inner peripheral surface of the housing outer ring51. A series of radial passages 110 in this ring 51 severally communi- 6cate with an annular inlet chamber 119 for the turbine wheel 98.

Partially covering the axially facing outer surfaces of the turbinewheels 96 and 98 are stationary cover members 120 and 121, respectively.Each of these members has a portion which opposes the vanes 102 on thecorresponding turbine wheel and is closely spaced for the land surfacesof such vanes. This close spacing is maintained by a series ofcircumferentially uniformly spaced lugs 122 arranged around theperiphery of the corresponding turbine wheel and preferably formedintegrally with the respective cover members 120 and 121. In the case ofthe member 120, its lugs 122 abut against the opposing outer end face ofthe housing outer ring 51. In the case of the other member 121, its lugs122 abut against the opposing outer end face of the other housing outerring 52. The lugs 122 are streamlined in contour and are inclined withrespect to the radius of the corresponding turbine wheel to provideinlet vanes, as best shown in FIG. 4. The spacers 123 between adjacentlugs 122 communicate with the corresponding turbine inlet chamber 112 or119. The chamber 112 is formed jointly by the housing outer ring 51,turbine cover 120 and end head 11. The chamber 119 is formed jointly bythe housing outer ring 52, turbine cover 121 and end head 12.

Means are provided for supplying pressurized working gas to the turbineinlet chambers 112 and 119 for driving the turbines 96 and 98. As shownin FIG. 2, the end' head 11 is provided with a pair of diametricallyopposed axial through passages 124 which at their inner ends severallycommunicate with the annular chamber 112. The outer end of each passage124 is covered by an attaching flange 125 having a nipple 126 whichforms an extension for the corresponding passage 124. Each of theseflanges 125 is shown in FIG. 1 as secured to the end head 11 by a pairof machine screws 128, the shanks of which are threadedly received inrecesses provided in the end head 11. a

In similar fashion, the other end head 12 is provided with a pair ofdiametrically opposed axially extending through passages 129 eachcovered by an attaching flange 130 having a nipple 13 1. The attachingflanges 130 are secured to the end head 12 in a similar manner to thatdescribed for the attaching flanges 125.

Gas flows from the annular inlet chambers 112 and 119 through therespective passages 123 and over the blades 102 on the respectiveturbine wheels 96 and 98 to rotat-ively drive these wheels. The spentWorking gas discharged by the turbine wheel 96 flows through a centralaxially extending hole 132 provided in the turbine cover 120. This hole132 is in alinement with an axially extending through hole 133 providedin the end head 11. The outer end of this passage 133 is covered by anattaching flange 134 having a nipple 135 as shown in FIG. 2. Theattaching flange 134 is secured to the end head 11 in any suitablemanner as by machine screws 136, four such screws being shown in FIG. 1.The shanks of these screws 136 are threaded into recesses provided inthe end head 11.

The other end head 12 has a central axially extending through pasage 138which at its inner end al-ines with a central axially extending hole 139provided in the turbine cover 121. The other end of the passage 138 iscovered by an attaching flange 140 having a nipple 141 and secured tothe end head 12 by machine screws (not shown) in a manner similar tothat described for the attaching flange 134.

Operation While the turbine driven centrifugal compressor unit mayhandle any desired gas, its opera-ion will be described in connectionwith the handling of ethylene gas. It is assir-med that this unit is thelast or topping stage of an array of compression apparatus. It isfurther assumed that ethylene gas under a pressure of say 20,000 p.s.i.is supplied to the inlet nipples 68 and 69.

It is further assumed that ethylene gas at a lower pressure, say 2500p.s.i. and derived from a lower stage of the aforementioned compressionapparatus is utilized as a working fluid for the turbines 96 and 98 andis therefore supplied to the nipples 126 and 131. This working fluid forthe turbines enters the annular turbine inlet chambers 112, 119 fromwhence it flows through the spaces 123, being directed therethrough bythe inclined guide vanes 122 into impingement with the blades 102 on theturbine wheels 96 and 98. Such impingement causes the turbine wheels 96and 98 to rotate in the same direction and thereby rotate the shaft 16to which these turbine wheels are fast, also in the same direction. Thespent turbine working gas is discharged through the outlet passages 133and 138 to the associated discharge nipples 135 and 141, respectively.Typically, turbine exhaust gas may have a pressure of 1,000 p.s.i. andis returned to a suitable point in the reciprocating compressor systemwhere the pressure is at the exhaust level of the drive turbine.

Adverting to the compressor part of the unit, the relatively highpressure inlet process gas entering through the nipples 68 and 69 flowsthrough the respective associated passages into the inlet passages 53leading to opposite sides of the impeller 29 adjacent the hub thereof.These streams of process gas are turned by the configuration of thepassages 46 into a radially outward direction and flow over the blading34 on opposite sides of the impeller 29 and are compressed bycentrifugal action.

Typically, the shaft and hence the impeller 29 which is fast thereto mayrotate at a high speed such as 70,000 r.p.m., being driven at this speedby the turbine wheels 96 and 98. With such high speed of rotation it hasbeen found desirable to dispose opposite the bladed sides of theimpeller the freely rotatable plates 71 and 72 which will assume someslower speed of rotation with respect to the rotating impeller. Rotationof the freely rotatable plates 71 and 72 is induced by thecircumferentially directed drag of the gas flowing between these platesand the impeller. The provision of the plates 71 and 72 has been foundto improve the efliciency of compression as compared to a situationwhere a stationary wall or surface opposes the blading on the rotatingimpeller.

The process gas is centrifugally compressed by the rotating impeller 29and collects in the annular chamber 81 from whence it is dischargedthrough the diffuser slots 63 into the annular groove 62. From thisgroove 62 the compressed process gas is discharged through the passage61 and out the outlet nipple 70.

With the compressor handling process gas having such a high pressure itis impossible to prevent the leakage of gas between relatively rotatingparts. Accordingly the high pressure inlet process gas which is presentin the inlet passages 53, 46, leaks through the annular radialclearances 89 and 90 and is equalized by reason of the axially extendingcommunicating passages or. grooves 33 in the central shaft section 18.This high pressure process gas leaks axially outwardly pass thelabyrinth seal means 91 and 92 to collect Within the internal housingchambers 86 and 88.

From these chambers gas flows through the connected passages 93-95 tothe corresponding opposing surfaces between the sleeve bearings 82, 83and shaft sections 21 and 22, respectively. The cylindrical shaftsection opposing the radial holes 94 acts as a valve closure for theinner ends of these holes and thereby controlsthe pressure of gas. Forexample, should the shaft tend to settle downwardly clue to gravity, asviewed in FIG. 3, the lower I holes 94 depicted in that figure will tendto be closed off more by the opposing peripheral surface of thecorresponding shaft section 21 or 22. This tends to increase thepressure in these lower passa ges94 and this pressure is utilized totend to lift the shaft. In this manner an annular film of gas isprovided between the opposing surfaces of the shaft and sleeve bearingsand thus the shaft floats on such gas film. This type of support doesnot require any conventional lubrication such as with oils or greases.In fact contamination of ethylene gas with oil or grease would bedeleterious.

Obviously with some necessary clearance provided between the opposingbearing and shaft surfaces, there will be additional axially outwardlydirected gas leakage. This gas leakage therefore flows pass thelabyrinth seal means 104 and 105 to collect in the annular grooves 106and 113, respectively. From the groove 106, the gas flows through theconnected passages 108-111 into the turbine inlet chamber 112. From thegroove 113 the gas flows through the connected passages 114416 and 118into the other turbine inlet chamber 119. By the time the leakage gasescapes through the branch outlets 111 and 118, its pressure will havebeen reduced to about 2500 p.s.i. so that this leakage gas comingleswith the working gas in the respective annular turbine inlet chambers112 and 119 at substantially the same pressure.

It will be seen that the symmetrical blading 34 on 0pposite sides of theimpeller 29 will not produce any resultant end thrust or axiallydirected thrust. Likewise, the drive turbine wheels 96 and 98, beingsimilar and arranged back to back, will not produce any resutlant end oraxially directed thrust. In fact, the whole design of the turbinecompressor unit is symmetrical and no special end thrust bearing meansneed be provided.

From the foregoing, it will be seen that the present invention providesa hermetically sealed high speed turbine driven high pressurecentrifugal compressor unit which accomplishes the various objectsstated supra. Modifications and changes may occur to those skilled inthe art without departing from the spirit of the present invention andtherefore the preferred embodiment shown and described is illustrativeand not limitative of the present invention, the scope of which isintended to be measured by the appended claims.

What is claimed is:

1. In a hermetically sealed turbine driven centrifugal compressor unit,the combination comprising a housing, a shaft, fluid type bearingssupported by said housing and journalling said shaft inwardly of eachend thereof so as to leave overhung shaft end portions, an impellerarranged within said housing intermediate said bearings and fast to saidshaft, symmetrical blading on opposite axially facing sides of saidimpeller, a pair of similar turbine wheels arranged within said housingand severally nonrotatively mounted on said overhung shaft end portionsand facing in opposite axial directions, fluid inlet passage means ofsaid turbines through which pressurized fluid is supplied, fluid inletpassage means for said impeller through which fluid under a higherpressure is supplied, and means conducting fluid leaking internally fromsaid impeller inlet passage means toward said turbine inlet plasiagemeans through said hearings to fluid float said s at.

2. In a hermetically sealed turbine driven centrifugal compressor unit,the combination comprising a housing, a shaft, fluid type sleevebearings supported by said housing and journalling said shaft inwardlyof each end thereof so as to leave overhung shaft end portions, animpeller arranged within said housing intermediate said bearings andfast to said shaft, symmetrical blading on opposite axially facing'sidesof said impeller, a pair of similar turbine wheels arranged within saidhousing and severally non-rotatively mounted on said overhung shaft endportions and facing in opposite axial directions, means providing fluidinlet passage on each axial side of said impeller and communicating withsaid impeller adjacent its radially inner end, and means supplying fluidinternally leaking from said passages to said hearings to fluid floatsaid shaft and including labyrinth seal means surrounding said shaft oneach side of said impeller intermediate the same and the correspondingone of said bearings, the inner end of each of said seal means being 'incommunicationwith the corresponding one of said the inner peripheralsurface'of the corresponding one of said bearings.

3. In a hermetically sealed turbine driven centrifugal compressor unit,the combination comprising a housing, a shaft, fluid type sleevebearings supported by said housing and journalling said shaft inwardlyof each end thereof so as to leave overhung shaft end portions, andimpeller arranged within said housing intermediate said bearings andfast to said shaft, symmetrical bl-ading on opposite axially facingsides of said impeller, a pair of similar turbine wheels arranged withinsaid housing and severally non-rotatively mounted on said overhung shaftend portions and facing in opposite axial directions, means providing afluid inlet passage on each axial side of said impeller andcommunicating with said impeller adjacent its radially inner end, andmeans supplying fluid internally leaking from said passages to saidbearings to fluid float said shaft and including labyrinth seal meanssurrounding said shaft on each side of said impeller intermediate thesame and the corresponding one of said bearings, the inner end of eachof 'said seal means being in communication with the corresponding one ofsaid passages, means establishing communication between the inner andopposing ends of said seal means, means providing a compartment at theouter end of each of said seal means and means establishingcommunication between each of said compartments and the inner peripheralsurface of the corresponding one of said bearings.

4. In a hermetically sealed turbine driven centrifugal compressor unit,the combination comprising a housing, a shaft, fluid type sleevebearings supported by said housing and journalling said shaft inwardlyof each end thereof so as to leave overhung shaft end portions, animpeller arranged within said housing intermediate said bearings andfast to said shaft, symmetrical blading on opposite peller andcommuncating with said impeller adjacent its radially inner end, meanssupplying fluid internally leaking from said passages to said bearingsto fluid float said shaft and including labyrinth seal means surroundingsaid shaft on each side of said impeller intermediate the same and thecorresponding one of said bearings, the inner end of each of said sealmeans being in communication with the corresponding one of saidpassages, means providing a compartment at the outer end of each of saidseal means and means establishing communication between each of saidcompartments and the inner peripheral suraxially facing sides of saidimpeller, a pair of similar turbine wheels arranged within said housingand sever-ally non-rotati-vely mounted on said overhung shaft endportions and facing in opposite axial directions, means providing afluid'inlet passage on each axial side of said impeller andcommunicating with said impeller adjacent its radially inner ends, andmeans supplying fluid internally leaking from said passages to saidbearings to fluid float said shaft and including labyrinth seal meanssurrounding said shaft on each side of said impeller intermediate thesame and the cor-responding one of said bearings, the inner end of eachof said seal means being in communication with the corresponding one ofsaid passages, means establishing communication between the inner andopposing ends of said seal means, means providing a compartment at theouter end of each of said seal means, means establishing communicationbetween each of said compartments and the inner peripheral surface ofthe corresponding one of said bearings and another labyrinth seal meanssurrounding said shaft and arranged between each of said bearings andthe corresponding one of said turbine wheels. 7

compressor unit, the combination comprising a housing, a shaft, fluidtype sleeve bearings supportedby said housing and journalling said shaftinwardly of each end thereof so as to leave overhung shaft end portions,an impeller arranged within said housing intermediate said bearings andfast to said shaft, symmetrical blading on opposite axially facing sidesof said impeller, a pair of similar turbine wheels arranged within saidhousing and severally non-rotatively mounted on said overhung shaft endportions and facing in opposite axial directions, means providing afluid inlet passage on each axial side of said im- V mediate saidbearings and fast to said shaft, symmetrical face of the correspondingone of said bearings, means providing an inlet passage associated witheach turbine wheel for supplying fluid to drive the same, and meansconducting fluid leaking past each of said hearings to the correspondingone of said turbine inlet passages.

6. In a hermetically sealed turbine driven centrifugal compressor unit,the combination comprising a housing including a barrel section and endheads, a shaft arranged entirely within said housing, fluid type sleevebearings supported by said housing and journalling said shaft inwardlyof each end thereof so as to leave overhung shaft end por- .tions, animpeller arranged within said housing intermediate said bearings andfast to said shaft, symmetrical blading on opposite axially facing sidesof said impeller, means providing a pair of fluid inlet passagesextending through said barrel section and leading to opposite sides ofsaid impeller adjacent its radially inner end, means providing a fluidoutlet passage extending from the periphery of said impeller throughsaid barrel section, a pair of similar turbine wheels arranged Withinsaid housing and severally non-rotatively mounted on said overhung shaftend portions and facing in opposite axial directions, means providing aworking fluid inlet passage for each of said turbine wheels andextending through the corresponding one of said end heads, meansproviding a working fluid outlet passage for each of said turbine wheelsand extending through the corresponding one of said end heads, meansconducting fluid leaking from said impeller inlet passages to the spacebetween the corresponding opposing peripheries of said sleeve hearingand shaft to fluid float said shaft, and means conduct-ing fluid leakingfrom each of said bearing spaces to the corresponding one of saidturbine inlet passages.

7. In a turbine driven centrifugal compressor unit, the combinationcomprising a housing, a shaft, bearings supported by said housing andjournalling said shaft inwardly of each end thereof so as to leaveoverhung shaft end portions, an impeller arranged within said housingintermediate said bearings and fast to said shaft, symmetrical bladingon opposite axially facing sides of said impeller, a pair of freelyrotatable plates arranged within said housing coaxially with saidimpeller and severally opposing the bladed sides thereof, and a pair ofsimilar turbine wheels arranged within said housing and severallynonrotatively mounted on said overhung shaft end portions and facing inopposite axial directions.

8. In a turbine driven centrifugal compressor unit, the combinationcomprising a housing, a shaft, bearings supported by said housing andjournalling said shaft inwardly of each end thereof so as to leaveoverhung shaft end portions, an impeller arranged within said housinginterbl-ading' on opposite axially facing sides of said impeller, a pairof freely rotatable plates arranged within said housing coaxial-ly withsaid impeller and severally opposing the bladed sides thereof, a bearingring rotatably supporting each of said plates and composed of long chainfluorinated polymers of ethylene such as tetrafluoroethy'lene, and apair of similar turbine wheels arranged within said hous-- ing andseverally non-rotatively mounted on said overhung shaft end portions andfacing in opposite axial directions.

9. In a turbine driven centrifugal compressor unit, the combinationcomprising a housing, a shaft, bearings supported by said housing andjournallingsaid shaft inwardly of each end thereof so as to leaveoverhung shaft end portions, an impeller arranged within said housingintermediate said bearings and fast to said shaft, symmetrical bladingon opposite axially facing sides of said impeller, a diffuser ringarranged within said housing and surrounding said impeller, a pair offreely rotatable plates arranged within said housing coaxially with saidimpeller and severally opposing the bladed sides thereof, an innerbearing ring rotatably supporting each of said plates on said housing,said diffuser ring and plates having overlapping portions, and a pair ofsimilar turbine wheels arranged within said housing and severallynon-rotatively mounted on said overhung shaft end portions and facing inopposite axial directions.

References Cited by the Examiner UNITED STATES PATENTS 1,171,926 2/16Carpenter 230-116 2,064,126 12/36 Schellens et a1. 230116 2,321,276 6/43De Bolt 10398 X 2,334,625 11/43 Heppner 10398 X 2,929,548 3/60 Crooks eta1. 230116 FOREIGN PATENTS 22,753 1/06 Austria. 418,900 9/25 Germany.

LAURENCE V. EFNER, Primary Examiner. ROBERT M. WALKER, Examiner.

1. IN A HERMETICALLY SEALED TURBINE DRIVEN CENTRIFUAL COMPRESSOR UNIT,THE COMBINATION COMPRISING A HOUSING, A SHAFT, FLUID TYPE BEARINGSSUPPORTED BY SAID HOUSING AND JOURNALLING SAID SHAFT INWARDLY OF EACHEND THEREOF SO AS TO LEAVE OVERHUNG SHAFT END PORTIONS, AN IMPELLERARRANGED WITHIN SAID HOUSING INTERMEDIATE SAID BEARINGS AND FAST TO SAIDSHAFT, SYMMERTICAL BLADING ON OPPOSTIE AXIALLY FACING SIDES OF SAIDIMPELLER, A PAIR OF SIMILAR TURBINE WHEELS ARRANGED WITHIN SAID HOUSINGAND SEVERALLY NONROTATIVELY MOUNTED ON SAID OVERHUNG SHAFT END PORTIONSAND FACING IN OPPOSITE AXIAL DIRECTION, FLUID INLET PASSAGE MEANS OFSAID TURBINES THROUGH WHICH PRESSURIZED FLUID IS SUPPLIED, FLUID INLETPASSAGE MEANS FOR SAID IMPELLER THROUGH WHICH FLUID UNDER A HIGHERPRESSURE IS SUPPLIED, AND MEANS CONDUCTING FLUID LEAKING INTERNALLY FROMSAID IMPELLER INLET PASSAGE MEANS TOWARD SAID TURBINE INLET PASSAGEMEANS THROUGH SAID BEARINGS TO FLUID FLOAT SAID SHAFT.